#include<iostream> 
using namespace std;
int main()
{
    int n,k;
    int comm(int n,int k); 
    cin>>n>>k;
    cout<<comm(n,k)<<endl;
    system("pause");
    return 0; 
} 

int comm(int n,int k)
{
    if(k>n)  return 0;
    else if( n==k || k==0 )  return 1;
    else return comm(n-1,k)+comm(n-1,k-1); 
} 
